IN8bio, Inc. (Nasdaq: INAB), a clinical-stage biopharmaceutical company developing innovative gamma-delta (γδ) T cell therapies for cancer and autoimmune diseases, today presented new preclinical data from its γδ T cell engager program, INB-619, at the 2025 American College of Rheumatology (ACR) Convergence Meeting in Chicago.

In preclinical SLE donor models, INB-619 achieved complete elimination of B cells with efficacy equivalent to approved CD19 and CD20 engagers, including the FDA-approved compounds blinatumomab and mosunetuzumab. The data demonstrated minimal secretion of adverse cytokines such as IL-6, a validated biomarker for cytokine release syndrome (CRS), at concentrations multiples lower than the currently marketed compounds tested.

INB-619’s targeted immune activation and cytokine-sparing design could allow for higher doses, deeper B cell depletion and immune reset that has not been observed with other protein engagers to date. INB-619 also selectively expanded γδ T cells from both SLE and healthy donors without activating CD4+ or CD8+ αβ T cells, supporting the potential for an improved safety and tolerability profile.

“These results demonstrate IN8bio’s unique know-how and capabilities with γδ T cell biology,” said William Ho, CEO and Co-Founder, IN8bio. “INB-619 is a γδ-TCE with innovative properties fully developed in-house. We achieved deep, consistent B cell depletion, independent of starting γδ T cell levels, with a potentially superior safety profile compared with existing T cell engagers. It’s an important validation of our platform and its potential to address both cancer and autoimmune disease.”

INB-619 is a potential first-in-class, CD19-targeted, pan-γδ T cell engager designed to activate and expand both major γδ T cell subsets, V-delta-1 (Vδ1+) and V-delta-2 (Vδ2+). This pan-γδ T cell expansion leads to deep B cell depletion, a key goal in B cell-driven autoimmune disorders such as SLE. By engaging both circulating and tissue-resident γδ T cells, INB-619 could enable more durable immune modulation in complex autoimmune diseases.

Conventional T cell engagers activate the CD3 receptor and can trigger toxicities, including CRS and immune effector cell-associated neurotoxicity syndrome (ICANs) that can be lethal. INB-619 uniquely targets through the γδ T cell receptor (γδ-TCR) and does not require CD3 engagement, which significantly reduces the potential for toxicities from cytokines or cellular exhaustion. INB-619’s unique ability to expand γδ T cells in vivo allows it to overcome the low baseline γδ T cell counts that have limited other γδ-TCE technologies in development.

The results highlight INB-619’s potential to transform the treatment of autoimmune diseases by harnessing the unique properties of γδ T cells to safely and precisely eliminate pathogenic B cells and drive immune reset. The data also demonstrated robust, dose-dependent B cell killing and γδ T cell expansion, maintaining a favorable cytokine profile consistent with the unique biology of γδ T cells. γδ T cells are specialized immune cells capable of potent killing activity with low or no cytokine release.

IN8bio is a clinical-stage biopharmaceutical company developing γδ T cell product candidates for unmet medical needs. Gamma-delta T cells are a specialized population of T cells that possess unique properties, including the ability to differentiate between healthy and diseased tissue. The company’s lead program, INB-100, is focused on acute myeloid leukemia evaluating haplo-matched allogeneic γδ T cells given to patients following a hematopoietic stem cell transplant. The company is also evaluating autologous DeltEx DRI γδ T cells, in combination with standard of care, for glioblastoma in its INB-200 and 400 programs, and INB-600, advancing novel γδ T cell engagers for potential oncology and autoimmune indications. For more information about IN8bio, visit www.IN8bio.com.